In the long-size wound twist tie of such a type, it is necessary that, in its repeatedly wound state onto a reel or the like, there is no slipping down of the tie into reel gap, no torsion and curl, no twining and tangling of ties, no loosening or disjoining from a reel and smooth drawing-out. Accordingly, soft PVC is used as a resin material for a material to be coated, a twist tie using a wire which has a big ability of forming a fixed shape as a core material is wound around a plastic reel or the like and the resulting one is often used in the case of binding a thing to be bound by means of a high-binding number of 50 to 100 bindings per minute.
On the other hand, due to considerations to environment in recent years, there has been a strong demand particularly in food companies, electric/electronic companies, etc. for a product where no wire is used in core material (or core part) and, further, substance of the material used therefor such as coating agent is a non-halogenous material such as an olefin resin.
In order to meet the demand as such, various ties have been proposed by the present applicant already. They are, for example, Japanese Utility Model Laid-Open No. 60/190,654 and Japanese Patent Laid-Open Nos. 11/293,577 and 2000/118,555 for a lamination twist tie using a plastic line as a core material and paper or olefin resin (e.g., PE, PP, PET or PBT) as a coating material; and U.S. Pat. No. 4,797,313, Japanese Patent Nos. 2,520,403and2,813,994, U.S. Pat. No. 5,154,964 and Japanese Patent Laid-Open No. 2000/095,267 for a non-core twist tie of an extrusion type having no core line in the core part where resin such as olefin is used and a wing part is subjected to a united extrusion molding together with the core part.
Thus, in Japanese Utility Model Laid-Open No. 60/190,654, there is a disclosure for a twist tie which is hardly corroded, is able to prevent injury of fingertip, does not cause electric leakage and is able to be used for a metal detector where a synthetic resin line such as polyester is used as a core line and a synthetic resin material such as polyethylene, polypropylene or polyester is used as a coating material.
In Japanese Patent Laid-Open No. 11/293,577, there is a disclosure for a lamination twist tie having a good operation ability for attachment and detachment where a synthetic resin line of polyethylene subjected to an elongating treatment is used as a core line and a plastic film such as a film vapor-deposited with polyester is used as a coating material and a method for manufacturing the same.
In Japanese Patent Laid-Open No. 2000/118,555, there is a disclosure for a lamination twist tie having the characteristics of (1) unpacking and back torsion are easily conducted without returning the bonded part to a loose state, (2) flexibility is available, (3) no projection of the core material is noted, etc. where a plastic line of a multi-filament type is used as a core line and nonwoven fabric, paper or plastic film is used as a coating material.
In U.S. Pat. No. 4,797,313 and Japanese Patent No. 2,520,403, there is a disclosure for a coreless twist tie prepared by means of an extrusion molding having no core line in the core part and, for example, there is a disclosure for a twist tie containing a polymer substance which is a thermoplastic polymer containing at least 50% of polyalkylene terephthalate, styrene-acrylonitrile copolymer, polystyrene and poly(vinyl chloride) having a glass transition temperature of higher than about 30° C., showing a glass/rubber transition behavior at the temperature of about 10 to 30° C. and having the characteristics that (1) it is able to be bound and tied by hand or by a mechanical device, (2) it is able to be bonded/tied, loosened and re-bonded within a wide temperature range and a tight binding is able to be retained, (3) it is able to be used in a microwave oven and (4) it is able to retain a tight binding even under a high-temperature treatment.
In Japanese Patent No. 2,813,994, there is a disclosure for a coreless twist tie using no core line in the core part which is composed of a crystalline thermoplastic synthetic resin such as polyethylene resin, polypropylene resin, polyamide resin, polybutylene terephthalate resin and polyethylene terephthalate resin and glass beads having a particle size of not larger than 60 μ and prepared by elongation where the elongation rate is 2.5-fold or more whereby it is easily twisted and is able to retain its twisted binding state.
In U.S. Pat. No. 5,154,964, there is a disclosure for a ribbon-shaped wireless twist tie having no core line in the core part which is easily twisted and easily loosened. The tie is prepared by elongation, to an extent of 2.5-fold or more, of a polymer resin having a degree of crystallization of 10 to 60% at the crystallization temperature of about 100 to 250° C.
In Japanese Patent Laid-Open No. 2000/095,267, there is a disclosure for a plastic-bound tie having no core line in the core part in which a tensile elasticity load of the convex part playing a role of the core is 100 to 625 kgf while that of the flat part playing a role of a wing is 20 to 120 kgf whereby the load of the former is twice or more of the load of the latter and two incompatible properties of easy deformation versus strong binding property are able to be available at the same time.
In those twist ties in which the core part has no core line or wire is not used for the core line of the core part and the material used for the coating material is constituted from a non-halogenous material such as olefin resin, improvement in their properties is significant and, in the shape being cut in a short size, they fully achieve their function and have been able to be used without problem. On the other hand however, ability of the core part for forming a fixed shape is essentially weaker than wire and, moreover, the coating material has higher hardness than soft PVC as compared with the conventional twist ties where wire is used as a core line and PVC is used as a coating material. Therefore, they are not convenient for a shape of being wound in a bundle like in the case of winding on a reel. Thus, during winding, transportation and actual use, there are resulted slipping down of the tie into gap of a reel, torsion of the tie itself, curl, twining and tangling of the tie and loosening or disjoining from a wound state and, as a result, there are generated many problems such as that a smooth drawing-out is not possible whereby the actual situation is that no completely satisfactory tie has been available yet.